This section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Various abbreviations that may appear in the specification and/or in the drawing figures are defined as follows:
3GPPThird Generation Partnership ProjectBSSBase Station SystemEDGEEnhanced Data Rates for Global EvolutionGSMGlobal System for Mobile communicationsGERANGSM/EDGE Radio Access NetworkMSmobile station (may also referred to as a UE)UMTSuniversal mobile telecommunications systemUTRANUMTS Terrestrial Radio Access NetworkEUTRAN evolved UTRAN (LTE)LTElong term evolutionNode Bbase stationBSSbase station subsystemeNBEUTRAN Node B (evolved Node B)UEuser equipment (also referred to as a MS)ULuplink (UE towards eNB)DLdownlink (eNB towards UE)RLCradio link controlRRCradio resource controlRRMradio resource managementMACmedium access controlOFDMAorthogonal frequency division multiple accessSC-FDMAsingle carrier, frequency division multiple accessPLCIDphysical layer cell identificationSACCHslow associated control channelNcellneighbor cellNCLneighbor cell listPSIpacket system informationRATradio access technologySISystem Information
A communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as E-UTRA) has been developed within 3GPP. A working assumption has been that the DL access technique will be OFDMA, and the UL access technique may be SC-FDMA.
One specification of interest in this regard is 3GPP TS 36.300, V8.3.0 (2007-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety.
The discussion below is related generally to GSM Mobile communications and inter-workings between multiple Radio Access Technologies (RATs), also referred to as multi-RAT. Mobile stations that support multiple RATs typically receive System Information (SI) messages for each of the RATs supported by GERAN whilst the MS is present within GERAN.
It is noted that at the time of this invention GERAN supported only UTRAN as an alternative RAT, although efforts have been made to enable the support of E-UTRAN. The SI and PSI messages contain information to identify allowed neighbor cells in each of the supported RATs, and measurement parameters to be applied when measuring these neighbor cells. The MS uses this information to measure the quality of the signal received from each of the neighbor cells and to verify its identity via some form of cell identifier. Then, if the measurement results meet some pre-defined criteria, depending on the mechanisms supported in the GERAN cell, the MS may decide by itself, or be commanded to, reselect to the neighbor cell of a different RAT.
With the addition of further RATs, notably E-UTRAN, a problem occurs due to the fragmentation of MSs resulting from different MSs supporting different multi-RAT classes. For instance, some MSs may support GERAN only, other MSs may support GERAN and UTRAN or GERAN and E-UTRAN, while still other MSs may support GERAN, UTRAN and E-UTRAN.
As such, each BSS needs to broadcast information relating to neighbor cells and parameters relating to measuring neighbor cells in all other supported RATs. In addition this information may be sent to mobiles that already have a connection with the network in instances of dedicated signaling messages such as a PACKET MEASUREMENT ORDER or a MEASUREMENT INFORMATION message. However, it is noted that not all multi-RAT mobiles need to receive SI for all supported RATs. Further, according to relevant 3GPP standards, the MS must receive all instances, known as a consistent set or full set, of the (P)SI messages before it begins measurement reporting and possible cell reselection to one of the identified neighbor cells. This can be seen to at least result in an MS having to process information that is not required by the MS.
The exemplary embodiments of the invention at least address these problems, as described above, and other problems.